|Publication number||US4712868 A|
|Application number||US 06/778,806|
|Publication date||Dec 15, 1987|
|Filing date||Sep 23, 1985|
|Priority date||Sep 23, 1985|
|Publication number||06778806, 778806, US 4712868 A, US 4712868A, US-A-4712868, US4712868 A, US4712868A|
|Inventors||Chi F. Tung, James C. Coderre|
|Original Assignee||Minnesota Mining And Manufacturing Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (18), Referenced by (38), Classifications (15), Legal Events (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Many retroreflective articles (which return light along substantially the same path that the light traveled to the article) would benefit from the ability to retroreflect light that impinges on the article over a wide range of angles. For example, when a retroreflective article extends in the direction of travel along a roadway, light from an oncoming vehicle strikes the article at a very high incidence angle (the angle between the light and a line perpendicular to the article). Most existing retroreflectors, such as the reflective sheeting used on traffic control signs, do not brightly retroreflect light striking the sheeting at such very high incidence angles.
The present invention provides a new reflective sheet material which retroreflects light that is incident on it over a wide range of angles, including very high incidence angles, as well as zero-degree incidence angle light (i.e., light that is perpendicular to the plane of the sheeting). This new sheet material can be used in a number of different ways, but one preferred use is to mount it alongside a roadway as a fence that can both serve as a glare screen and provide delineation for the roadway. Briefly, the new sheet material comprises retroreflective sheeting laminated to a base sheet, with the laminated sheet assembly being slit in an array of spaced discontinuous slits and expanded so that openings occur at the slits. Portions of the laminated sheet assembly between the slits bend or twist out of the plane they originally occupied, whereby the retroreflective sheeting is aligned to reflect over a wide range of angles. Various forms of retroreflective sheeting can be used, including (1) sheeting that comprises a monolayer of transparent microspheres and a layer of specularly reflective material underlying the microspheres and (2) sheeting that comprises cube-corner retroreflective elements.
FIG. 1 is a top view of an intermediate product prepared in the course of preparing a representative sheeting of the invention;
FIG. 2 is an enlarged sectional view through the intermediate product shown in FIG. 1;
FIG. 3 is a top view of a completed representative sheeting of the invention;
FIG. 4 is a sectional view through a portion of sheet material of the invention taken along the lines 4--4 in FIG. 3;
FIG. 5 is a perspective view of an alternative sheet material of the invention;
FIG. 6 is a sectional view like the view shown in FIG. 4 through a portion of a different sheet material of the invention; and
FIG. 7 is an enlarged sectional view like the view shown in FIG. 2 through another representative product of the invention.
FIGS. 1-4 show a representative sheet material of the invention 10 in various stages of preparation and from different points of view. The sheet material is typically prepared by first laminating a retroreflective sheeting 11 to a base sheet 12 to form an intermediate product such as illustrated in FIGS. 1 and 2. A shown in FIG. 2, a typical and preferred retroreflective sheeting 11, known as embedded lens sheeting, comprises a monolayer of transparent microspheres 13 covered on the front or top with a flat-surfaced layer 14 and cover film 15, and covered on the bottom by a spacing layer 16, which is conformed to the microsphere surface. The layers 14, 15, and 16 are made from transparent polymeric materials such as alkyd resins or acrylic resins. A specularly reflective layer 17, preferably vapor-deposited aluminum, covers the conformed surface of the spacing layer 16, and a layer of adhesive 18 is coated over the specularly reflective layer. The adhesive can be a pressure sensitive, heat-activated, or solvent-activated adhesive. For purposes of the invention, heat-activated adhesives are generally preferred.
Other forms of retroreflective sheeting may also be used, including reflective sheeting as described in U.S. Pat. No. 4,367,920; exposed lens microsphere-based reflective sheeting as described in U.S. Pat. No. 2,326,634, and cube-corner reflective sheeting as taught in U.S. Pat. No. 2,310,790 (especially forms in which the cube-corner surface is metallized and an adhesive is coated on the metallized surface). A representative cube-corner reflective sheet material of the invention is shown in Figure 7. The sheet material includes a cube-corner sheeting 28 such as described in FIG. 7 of U.S. Pat. No. 2,310,790. That sheeting comprises a transparent film 30 formed on its back surface with cube-corner elements 31, which are covered with a layer of metal 33. A layer of adhesive 32 covers the metal and adheres the material to a base substrate 29.
The base sheet 12 to which the retroreflective sheeting is laminated can be a variety of materials such as steel or aluminum sheet, sheets of engineering plastics or reinforced plastics, an elastomeric substrate such as polyurethane or styrene-butadiene rubbers, or a fabric such as canvas or rubberized canvas. The base sheet may be coated or primed to improve its adhesion to the retroreflective sheeting, to improve its weatherability, or for other reasons.
Retroreflective sheeting is often applied on both sides of the base sheet to provide a sheet material that is retroreflective on both sides.
After lamination, the intermediate product is slit with an array of slits 20 which are discontinuous and separated from one another. The slits are generally in a parallel pattern and located so that when the sheet material is expanded or stretched, a mesh-like structure is formed with the slit areas forming openings in the mesh. In some operations, the slitting tool is designed to expand the sheeting during the slitting operation, so that the sheeting is simultaneously slit and expanded. In other operations, expanding is performed subsequent to slitting. The slits are preferably in an ordered pattern so that a uniform mesh is formed.
As shown in FIG. 4, after expansion, portions 21 of the sheet material between slits become twisted or bent about 45°. Different portions are twisted different amounts, with some portions being essentially untwisted or unbent, which means that the sheet material will retroreflect through a wide range of incidence angles. Twisting or bending can occur in a single angular direction; i.e., as shown in FIG. 4, all the portions 21 are twisted in the direction of the arrow 22.. Alternatively, the portions between slits may be twisted or bent in different directions. In one alternative, shown in FIG. 5, a single portion 21a between slits is bent in two directions. Sheet material having two different directions of bending has the advantage that it offers better reflection in two directions of viewing, e.g., the two directions represented by the arrows 23 and 24 in FIG. 5.
The spacing between the slits may vary depending upon the intended use for the sheet material and the strength of the sheet material. For use as a glare screen alongside a roadway, the spacing should be such that when viewed at a 45° angle, the sheet material blocks visibility. However, the sheet material should be sufficiently open so that viewers looking through the sheet material at a 0° incidence angle, i.e., perpendicularly to the sheet material, can see through the sheet material.
After slitting and expanding, it may be desirable to coat the sheet material with a transparent polymeric film-forming material so as to seal the cut edges of the sheeting and function as a protective coating for the sheeting.
FIG. 6 is a cross-sectional view showing such a coated sheeting 25, comprising a sheet material as shown in FIG. 4 including a retroreflective sheeting 11 laminated to a base sheet 12 slit and stretched in the manner shown in FIG. 4 and then coated with a coating material 26. Also, the coating may complete the optics of the system (e.g., the top coat may provide the top layer of sheeting such as discussed in FIG. 6 of U.S. Pat. No. 4,367,920). Useful polymers for such a coating include acrylics, epoxies, and silicones or blends thereof. The polymers may be applied from a solution, e.g., by spraying or dipping the sheet material. In some cases, the sheet material may be encased completely in a continuous solid film whereupon the retroreflective sheeting is further protected from contact. For example, such an encased sheet material can be used as a pavement marking on a roadway and the retroreflective sheeting is protected from contact by the wheels of vehicles traveling on the roadway. Since the retroreflective sheeting includes twisted portions, high-incidence-angle light from oncoming vehicles would be retroreflected. The sheet material may be wrapped around a barrel and will reflect over its full length.
In the case of a pavement-marking sheet material or tape, the spacing between the slits should be rather narrow, such as on the order of 0.5 to 3 millimeters, so that in their twisted form they still allow the sheet material to have a minimum thickness.
Sheet material prepared using fabric as a substrate can form light-weight, portable reflective barricades. Normally, the sheet material can be expanded 1/2 to 3 times its original width after it has been slit.
A legend can be applied to sheet material of the invention, typically before slitting, whereupon the sheet material may present a message. For example, such a legend-bearing sheet material can be used as a sign in areas that experience high wind, with the wind pressure being reduced because of the openings through the sheet material of the invention.
Another use of sheet material of the invention is on signs at a curve on a roadway. Due to the broad angularity of the sheet material (i.e., the ability to reflect through a wide range of incidence angles), the sign can be visible even as motorists travel around the curve.
Sheet material of the invention can be mounted at certain locations, such as in a tunnel, where space is too limited to install a regular traffic control sign. Because portions of the sheet material are twisted, the sheet material can present a message that is viewable and legible even though the sign is disposed at an angle of 45° or 60° to the direction of traffic.
The sheet material of the invention will be further illustrated by the following example. An embedded-lens retroreflective sheeting available from 3M as "Scotchlite" Brand Commercial Grade, Reflective Sheeting, No. 850, which exhibits 100 percent elongation at break and carries a heat-activated adhesive, was laminated to a 0.125-inch-thick (3-millimeter-thick) steel substrate by heat lamination. The composite sheet assembly was then slit and expanded two to three times its original length on a conventional expanding machine. Thereupon. the slit and expanded sheet material was clear-coated by dipping in an alkyd resin solution.
When mounted alongside a roadway, the sheet material formed a glare screen which prevented light from the headlights of oncoming traffic in the opposite lane from blinding approaching drivers and which also provided reflection to assist drivers to determine their position in the lane of travel.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2310790 *||Nov 19, 1937||Feb 9, 1943||Optical reflecting material|
|US2326634 *||Dec 26, 1941||Aug 10, 1943||Minnesota Mining & Mfg||Reflex light reflector|
|US2697832 *||Apr 4, 1951||Dec 28, 1954||Stich Karl||Rainproof ventilated material|
|US3069796 *||Nov 13, 1958||Dec 25, 1962||Rudolf G Ruter||Camouflage material|
|US3442275 *||Sep 21, 1967||May 6, 1969||Wayne R Ternes||Combination utility device for hunters|
|US3453039 *||Jul 16, 1965||Jul 1, 1969||Osborne Harold Norman||Composite light transmitting and light reflecting panels and the like|
|US3582108 *||Sep 26, 1968||Jun 1, 1971||Ewell Lee Carlton||Vehicle splash guard|
|US3703432 *||Nov 18, 1970||Nov 21, 1972||Koski John T||Rainproof ventilated plastic sheet material for rainwear and method of making same|
|US3716445 *||Jun 24, 1970||Feb 13, 1973||Lemelson J||Reflex reflective sheeting|
|US3790431 *||Jan 24, 1972||Feb 5, 1974||Minnesota Mining & Mfg||Light-transmissive retroreflective sheeting|
|US3836226 *||Jul 23, 1973||Sep 17, 1974||Cechetini J||Reflective pavement marker|
|US3922433 *||Jun 8, 1973||Nov 25, 1975||Aluminum Co Of America||Aluminous metal with glass beads bonded to a metal substrate|
|US3985599 *||Mar 5, 1974||Oct 12, 1976||Pierre Lepoutre||Slit film|
|US4023889 *||Feb 24, 1975||May 17, 1977||Morgan Adhesives Company||Retroreflective laminate|
|US4025159 *||Feb 17, 1976||May 24, 1977||Minnesota Mining And Manufacturing Company||Cellular retroreflective sheeting|
|US4323605 *||Jan 21, 1980||Apr 6, 1982||Brunswick Corporation||Camouflage incising geometry|
|US4347284 *||Nov 3, 1980||Aug 31, 1982||Hiraoka & Co., Ltd.||White cover sheet material capable of reflecting ultraviolet rays|
|US4367920 *||Jun 19, 1981||Jan 11, 1983||Minnesota Mining And Manufacturing Company||Retroflective sheeting|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4825801 *||Oct 5, 1987||May 2, 1989||The United States Of America As Represented By The Director Of National Security||Tamper indicating seal and method for making the same|
|US5175646 *||May 24, 1990||Dec 29, 1992||Eden Elizabeth A||Reflective roll-up signs|
|US5223312 *||Nov 21, 1991||Jun 29, 1993||Langille John D||Multiple retroreflective striping method and structure|
|US5450236 *||Feb 4, 1991||Sep 12, 1995||Storra Aktiebolag||Reflector, especially for display signs and road signs and a sign manufactured thereof|
|US5575339 *||Mar 31, 1995||Nov 19, 1996||Alhamad; Shaikh G. M. Y.||Compositions of matter for stopping fires, explosions and oxidations of materials and build up of electrostatic charges and method and apparatus for making same|
|US5738175 *||Apr 30, 1997||Apr 14, 1998||Alhamad; Ghaleb Mohammad Yassin||Compositions of matter for stopping fires, explosions and oxidations of materials and build up of electrostatic charges and method and apparatus for making same|
|US5763049 *||Apr 30, 1996||Jun 9, 1998||Minnesota Mining And Manufacturing Company||Formed ultra-flexible retroreflective cube-corner composite sheeting with target optical properties and method for making same|
|US5770124 *||Apr 30, 1996||Jun 23, 1998||Minnesota Mining And Manufacturing Company||Method of making glittering cube-corner retroreflective sheeting|
|US5814355 *||Apr 30, 1996||Sep 29, 1998||Minnesota Mining And Manufacturing Company||Mold for producing glittering cube-corner retroreflective sheeting|
|US5816332 *||Jun 6, 1995||Oct 6, 1998||Alhamad; Shaikh Ghaleb Mohammad Yassin||Compositions of matter stopping fires, explosions and oxidations of materials and build up of electrostatic charges|
|US5840405 *||Apr 30, 1996||Nov 24, 1998||Minnesota Mining And Manufacturing Company||Glittering cube-corner retroreflective sheeting|
|US5948488 *||Apr 30, 1996||Sep 7, 1999||3M Innovative Properties Company||Glittering cube-corner article|
|US6067143 *||Jun 4, 1998||May 23, 2000||Tomita; Akira||High contrast micro display with off-axis illumination|
|US6089325 *||Apr 14, 1998||Jul 18, 2000||Yassin Alhamad; Shaikh Ghaleb Mohammad||Compositions of matter for stopping fires, explosions and oxidations of materials and build up of electrostatic charges and method and apparatus for making same|
|US6117062 *||Nov 21, 1995||Sep 12, 2000||Alhamad; Shaikh Ghaleb Mohammad Yassin|
|US6155689 *||Dec 15, 1998||Dec 5, 2000||Reflexite Corporation||Perforated retroreflective film|
|US6303058||Oct 30, 1998||Oct 16, 2001||3M Innovative Properties Company||Method of making profiled retroreflective marking material|
|US6451408 *||Apr 2, 1999||Sep 17, 2002||3M Innovative Properties Company||Retroreflective article|
|US6481857||Dec 5, 2000||Nov 19, 2002||Reflexite Corporation||Perforated retroreflective film|
|US6629016 *||Mar 28, 2002||Sep 30, 2003||Amerimax Diversified Products, Inc.||Apparatus and method of manufacturing expanded sheet metal|
|US6703108||Aug 29, 2000||Mar 9, 2004||3M Innovative Properties Company||Wet retroreflective marking material|
|US6736519||Sep 25, 2002||May 18, 2004||Reflexite Corporation||Perforated retroreflective film|
|US7616111||Nov 10, 2009||Carestream Health, Inc.||System to monitor the ingestion of medicines|
|US7782189||Feb 9, 2006||Aug 24, 2010||Carestream Health, Inc.||System to monitor the ingestion of medicines|
|US8479395 *||Apr 8, 2009||Jul 9, 2013||Zephyros, Inc.||Method for improved reinforcement baffling and sealing|
|US8564432||Nov 9, 2009||Oct 22, 2013||Carestream Health, Inc.||System to monitor the ingestion of medicines|
|US8677716 *||Aug 5, 2003||Mar 25, 2014||Jeffrey A. Anderson||Metal framing member and method of manufacture|
|US9058530||Sep 30, 2013||Jun 16, 2015||Carestream Health, Inc.||System to monitor the ingestion of medicines|
|US20040093822 *||Aug 5, 2003||May 20, 2004||Anderson Jeffrey A.||Metal framing member and method of manufacture|
|US20050185279 *||Jan 18, 2005||Aug 25, 2005||Reflexite Corporation||Durable, open-faced retroreflective prismatic construction|
|US20050206123 *||Feb 25, 2005||Sep 22, 2005||Young Scott J||Non-rotating bicycle wheel display disk|
|US20070008112 *||Jun 20, 2005||Jan 11, 2007||Edward Covannon||System to monitor the ingestion of medicines|
|US20070008113 *||Feb 9, 2006||Jan 11, 2007||Eastman Kodak Company||System to monitor the ingestion of medicines|
|US20100259059 *||Apr 8, 2009||Oct 14, 2010||Zephyros, Inc.||Method for improved reinforcement baffling and sealing|
|US20130180090 *||Aug 7, 2012||Jul 18, 2013||Jeffrey A. Anderson||Method of manufacturing a metal framing member|
|US20140168163 *||Mar 31, 2013||Jun 19, 2014||Subtron Technology Co., Ltd.||Optical touch sensing structure|
|CN102438882B||Apr 2, 2010||Jul 9, 2014||泽菲罗斯公司||Method for improved reinforcement baffling and sealing|
|WO1999031534A1 *||Dec 15, 1998||Jun 24, 1999||Reflexite Corp||Perforated retroreflective film|
|U.S. Classification||359/514, 359/601, 428/136, 359/541, 359/532, 359/531, 428/135|
|International Classification||G02B5/124, G02B5/128|
|Cooperative Classification||G02B5/124, G02B5/128, Y10T428/24314, Y10T428/24306|
|European Classification||G02B5/124, G02B5/128|
|Sep 23, 1985||AS||Assignment|
Owner name: MINNESOTA MINING & MANUFACTURING COMPANY, SAINT PA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:TUNG, CHI F.;CODERRE, JAMES C.;REEL/FRAME:004460/0684
Effective date: 19850919
|Jun 21, 1988||CC||Certificate of correction|
|Apr 8, 1991||FPAY||Fee payment|
Year of fee payment: 4
|Mar 31, 1995||FPAY||Fee payment|
Year of fee payment: 8
|Jul 6, 1999||REMI||Maintenance fee reminder mailed|
|Dec 12, 1999||LAPS||Lapse for failure to pay maintenance fees|
|Feb 22, 2000||FP||Expired due to failure to pay maintenance fee|
Effective date: 19991215